Heat-shrinkable tubing (HST) is a shrinkable plastic tube often used to insulate electrical wires. HST provides abrasion resistance and environmental sealing protection for stranded and solid wire conductors, connections, joints, and terminals used in various electrical applications. HST may also be used to repair damaged insulation on electrical wires, bundle wires together, or create cable entry seals. As stated above, HST may be a single-walled system or a multi-walled system, where the multi-walled system includes at least one heat-shrinkable layer and at least one layer of a sealant system. HST is commonly manufactured from fluoropolymers or polyolefins, which shrink radially when heated. The process of shrinking an HST is referred to as “recovering” the HST and the predetermined temperature at which an HST starts to recover is referred to as its “recovery temperature”. As an HST recovers/shrinks, it exerts an inward force against the item or items it surrounds, which is referred to as the “hoop stress” of the HST. More specifically, hoop stress, also known as cylinder stress, is the force exerted circumferentially (perpendicular both to the axis and to the radius of the object) in both directions on every particle in the tubing or cylinder wall. The degree of hoop stress is determined by certain HST characteristics, such as the type of base material, the wall thickness, the degree of crosslinking, and the degree of expansion. Hoop stress is also affected by certain process parameters, such as temperature of recovery and degree of recovery.
Stub splice or end splice connections are typically used to attach at least two electrical wires at an end of the wires. The spliced electrical wires may be crimped or soldered together at the connected end. Electrical wires to be connected by splicing may include single-wire and multi-wire configurations. Multi-wire configurations have created significant challenges with regard to sealing the wire-wire or wire-connector-wire interface area on such connections. External sealant systems that include the use of HST and an adhesive/sealant layer have been previously used to create a water-tight seal between and outside of the electrical wires attached to the terminal. However, conventional sealant systems are not capable of sealing the multiple electrical wires (e.g., six or more wires) included in multi-wire configurations in a simple and reliable manner. Failure to seal the multiple electrical wires may permit water or moisture ingress and/or transfer between wires.
To overcome the limitations of sealing systems that involve the use of external adhesive and HST, the currently-used industrial approach involves a multi-component, multi-step process. This process is labor-intensive and expensive. Therefore, there is an ongoing need for a sealing system for use with stub splice or end splice connectors that meets all functional requirements in a simplistic, reliable, and cost-effective manner.